1. Field of the Invention
This invention generally relates a dynamic damper and a flywheel assembly. More specifically, the present invention relates to a dynamic damper, which operates in accordance with an operation of an input shaft of a transmission for dampening a vibration.
2. Background Information
In connection with such a dynamic damper and a flywheel assembly, the assignee has already developed prior arts disclosed in Japanese Laid-Open Patent Publication No. 6-48031 (1994) and others.
In the above prior arts, a second flywheel forming a mass portion is coupled to a drive and transmission system through a torsional damper mechanism to dampen a torsional vibration on the drive and transmission system only when a clutch disk is pressed against a first flywheel. Thereby, an operation impeding shifting of the transmission is suppressed in a disengaged state of a clutch while suppressing gear noises (neutral noises) of the transmission in a neutral state as well as vibrations and noises of the transmission during driving of a vehicle.
As one of employable structure for improving dampening characteristics, the dynamic damper may use rubber members in place of coil springs, which have been employed in torsional dampers. For example, as shown in FIG. 13, a second flywheel 71 may be coupled to an input shaft 9 of a transmission in a drive and transmission system through an annular rubber member 72.
In the structure including the annular rubber member 72 as shown in FIG. 13, the rubber member 72 operating between the second flywheel 71 and the input shaft 9 of the transmission is primarily subjected to a shearing force, and therefore shearing deform occurs therein. Therefore, joined portions of the rubber member 72 and the second flywheel 71 may be separated from each other and/or the rubber member 72 may be deteriorated due to the shearing stress. For avoiding these disadvantages, it is necessary to reinforce the above portions and/or increase the rigidity thereof, resulting in increase in cost. If the rigidity of the rubber member is increased, then the intended dampening characteristics may not be obtained.
In view of the above, there exists a need for a dynamic damper and a flywheel assembly which overcomes the above-mentioned problems in the prior art. This invention addresses these needs in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.